Sheet material transposition for sorting apparatus

ABSTRACT

A displacement system and sorting apparatus for transposing the orientation of mailpiece from a first position to a second position such that the mailpiece may occupy a reduced space envelope within sortation bins/trays of a mailpiece sorter. The displacement system comprises first and second pairs of cooperating elements each defining a nip for accepting first and second portions, respectively, of the mailpiece therebetween. Further, the system includes a means for driving the first and second pairs of cooperating elements such that the first and second portions of mailpiece are each conveyed along a feed path at different velocities thereby transposing the mailpiece about an axis and changing the orientation of the mailpiece from the first to the second positions. The cooperating elements may include rolling elements such as nip rollers, spherical elements or belt pairs. The sortation bins/trays are adapted to support the short edge while guiding the long edge of the mailpiece. That is, the base of the bins/trays supports the on-edge width dimension of the mailpiece and sidewalls substantially normal to the base support the length dimension of the mailpiece.

TECHNICAL FIELD

This invention relates to apparatus for re-orienting sheet material, and more particularly, to an apparatus for transposing a mailpiece ninety degrees from an on-edge horizontal orientation to an on-edge vertical orientation to reduce the space occupied by a mailpiece sorter.

BACKGROUND ART

Mailpiece sorters are often employed by service providers, including delivery agents, e.g., the United States Postal Service USPS, entities which specialize in mailpiece fabrication, and/or companies providing sortation services in accordance with the Mail Manifest System (MMS). Regarding the latter, most postal authorities offer large discounts to mailers willing to organize/group mail into batches or trays having a common destination. Typically, discounts are available for batches/trays containing a minimum of two hundred (200) mailpieces.

The sorting equipment organizes large quantities of mail destined for delivery to a multiplicity of destinations, e.g., countries, regions, states, towns and/or postal codes, into smaller, more manageable, trays or bins of mail for delivery to a common destination. For example, one sorting process may organize mail into bins corresponding to various regions of the U.S., e.g., northeast, southeast, mid-west, southwest and northwest regions. Subsequently, mail destined for each region may be sorted into bins corresponding to the various states of a particular region e.g., bins corresponding to New York, New Jersey, Pennsylvania, Connecticut, Massachusetts, Rhode Island, Vermont, New Hampshire and Maine. Yet another sort may organize the mail destined for a particular state into the various postal codes within the respective state.

The efficacy and speed of a mailpiece sorter is generally a function of the number of sortation sequences or passes required to be performed. Further, the number of passes will generally depend upon the diversity/quantity of mail to be sorted and the number of sortation bins available. At one end of the spectrum, a mailpiece sorter having four thousand (4,000) sorting bins or trays can sort a batch of mail having four thousand possible destinations, e.g., postal codes, in a single pass. At the other end of the spectrum, a mailpiece sorter having as few as eight (8) sortation bins (i.e., using a RADIX sorting algorithm) may require as many as five (5) passes though the sortation equipment to sort the same batch of mail i.e., mail to be delivered to four thousand (4,000) potential postal codes. The number of required passes through the sorter may be evaluated by solving for P in equation (1.0) below:

P^((# of Bins))=# of Destinations  (1.0)

In view of the foregoing, a service provider typically weighs the technical and business options in connection with the purchase and/or operation of the mailpiece sortation equipment. On one hand, a service provider may opt to employ a large mailpiece sorter, e.g., a sorter having one hundred (100) or more bins, to minimize the number of passes required by the sortation equipment. On the other hand, a service provider may opt to employ a substantially smaller mailpiece sorter e.g., a sorter having sixteen (16) or fewer bins, knowing that multiple passes, and consequently, additional time/labor will be required to sort the mail.

The principal technical/business issues include, inter alia: (i) the number/type of mailpieces to be sorted, (ii) the value of discounts potentially available through sortation, (iii) the return on investment associated with the various mailpiece sortation equipment available and (iv) the cost and availability of labor. FIG. 1 depicts a conventional linear mailpiece sorter 100 having a plurality of sortation bins or collection trays 110 disposed on each side of a linear sorting path SP. In operation, the mailpieces 114 are first stacked on-edge in a feeder module 116 and fed toward a singulation belt 120 by vertical separator plates 122. The plates 122 are driven along and by a feed belt 124 which urges the mailpieces 114 against the singulation belt 120. As a mailpiece 114 engages the singulation belt 120, the mailpiece 114 is separated from the stack and conveyed along the sorting path SP. Inasmuch as the singulation belt 120 and sorting path SP are disposed orthogonally of the feed path FP, each mailpiece 114 may be conveyed directly along the sorting path SP without any further requirements to manipulate the direction and/or orientation of the mailpiece 114, e.g., a right-angle turn.

As each mailpiece 114 is conveyed along the sorting path SP, a mailpiece scanner 126 reads certain information, i.e., identification, destination, postal code information, etc., contained on the face surface of the mailpiece 114 for input to a processor 130. Inasmuch as each of the sortation bins or collection trays 110 corresponds to a pre-assigned location in the RADIX sortation algorithm, the processor 130 controls a plurality of diverters 134 (i.e., one per collection tray 110) to move into the sorting path SP at the appropriate moment time to collect mailpieces 114 into the collection trays 110. That is, since the mailpiece sorter 110 knows the identity and location of each mailpiece 114 along the sorting path SP, the processor 130 issues signals to rapidly activate the diverters 134 so as to re-direct a particular mailpiece 114 into its pre-assigned collection tray 110. A linear mailpiece sorter of the type described above is manufactured and distributed by Pitney Bowes Inc. located in Stamford, State of Connecticut, USA, under the tradename “Olympus II”.

As mentioned in a preceding paragraph, the total space available to a service provider/operator may prohibit/preclude the use of a large linear mailpiece sorter such as the type described above. That is, since each collection tray 110 must accommodate a conventional type-ten (No. 10) mailpiece envelope, each tray 110 spans a distance slightly larger than one foot (1′) or about fourteen inches (14″). As a result, a linear mailpiece sorter can occupy a large area or “footprint”, i.e., requiring hundreds of lineal feet and/or a facility the size of a conventional aircraft hanger.

In an effort to accommodate operators with less available space/real estate, other mailpiece sortation devices are available which employ a multi-tiered bank of collection trays (i.e., arranged vertically). These sortation devices (not shown) include an intermediate elevation module disposed between the feeder and bank of collection trays. More specifically, the elevation module includes a highly inclined table or deck for supporting a labyrinth of twisted conveyor belt pairs. The belt pairs capture mailpieces therebetween and convey mailpieces along various feed paths which are formed by a series of “Y”-shaped branches. Each Y-shaped branch/intersection diverts mailpieces to one of two downstream paths and additional branches downstream of each path increase the number of paths by a factor of two. Further, each branch functions to change the elevation of a mailpiece to feed the multi-tiered arrangement of collection trays. A multi-tiered mailpiece sorter of the type described above is manufactured and distributed by Pitney Bowes Inc. located in Stamford, State of Connecticut, USA, under the tradename “Olympus II”.

The multi-tiered mailpiece sorters can significantly reduce the space/footprint required by linear mailpiece sorters and multi-tiered mailpiece sorters are costly to fabricate, operate and maintain. Typically, these multi-tiered mailpiece sorters are nearly twice as costly to fabricate and maintain as compared to linear mailpiece sorters having the same or greater sorting capacity.

In addition to the difficulties associated with space and expense, the mailpiece sorters described above are highly complex, require highly-skilled technicians to perform maintenance, and, if not maintained properly, can result in damage to sorted mailpieces. For example, if particulate matter (e.g., paper dust) from envelopes is allowed to accumulate along the sorting path and/or in the actuation mechanisms of a diverter, the mailpiece sorter can become prone to paper jams. In addition to damage caused by jamming, the sortation order of the mailpieces, which is critical to perform a RADIX sort, can inadvertently be altered.

A need, therefore, exists for a mailpiece sorter and displacement system therefor having a reduced footprint for space efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate presently preferred embodiments of the invention and, together with the detailed description given below, serve to explain the principles of the invention. As shown throughout the drawings, like reference numerals designate like or corresponding parts.

FIG. 1 is a top view of a prior art mailpiece sorter including a plurality of sorting bins disposed on each side of a mailpiece sorting path.

FIG. 2 is a top view of a mailpiece sorter incorporating the teachings of the present invention wherein a plurality of sorting bins are disposed to each side of the mailpiece sorting path and wherein a displacement module, interposing the mailpiece feeder and the sorting bins, transposes each mailpiece from a horizontal (i.e., lengthwise) orientation to a vertical (i.e., edgewise) orientation.

FIG. 3 depicts a side schematic view of a plurality of cooperating rollers, i.e., pairs of rollers, which are differentially controlled to feed a mailpiece on-edge while simultaneously acting on portions of the mailpiece envelope to transpose the orientation of the mailpiece.

FIG. 4 depicts an enlarged top view of the displacement module including a processor for controlling a plurality of rotary actuators or motors which drive the cooperating rollers

FIG. 5 depicts the speed profile of the rollers wherein the motors are controlled to alternately linearly displace and rotationally position each mailpiece along the feed path.

FIG. 6 depicts an alternate embodiment of the invention wherein sensors provide mailpiece position feedback to the processor such that corrective action can be taken, i.e., a modification to the speed profile when the actual mailpiece position deviates from a scheduled mailpiece position.

FIG. 7 is a sectional view taken substantially along line 7-7 of FIG. 2 depicting a view through sortation bins/trays of a sortation bin module.

SUMMARY OF THE INVENTION

A displacement system and sorting apparatus is provided for transposing the orientation of mailpiece from a first position to a second position such that the mailpiece may occupy a reduced space envelope within sortation bins/trays of a mailpiece sorter. The displacement system comprises first and second pairs of cooperating elements each defining a nip for accepting first and second portions, respectively, of the mailpiece therebetween. Further, the system includes a means for driving the first and second pairs of cooperating elements such that the first and second portions of mailpiece are each conveyed along a feed path at different velocities thereby transposing the mailpiece about an axis and changing the orientation of the mailpiece from the first to the second positions. The cooperating elements may include rolling elements such as nip rollers, spherical elements or belt pairs. The sortation bins/trays are adapted to support the short edge while guiding the long edge of the mailpiece. That is, the base of the bins/trays support the on-edge width dimension of the mailpiece and sidewalls substantially normal to the base, support the length dimension of the mailpiece.

DETAILED DESCRIPTION

A displacement module or system is described for handling mailpiece in a sorting apparatus. The displacement system transposes mailpiece from a first on-edge orientation/position to a second on-edge orientation/position, substantially ninety-degrees (90°) from the angular position of the first position. The angular displacement or transposition allows mailpieces to be stacked within trays of a mailpiece sorter which, in combination, reduce the overall length requirements of the sorter and, consequently, the space requirements thereof. As a result, a mailpiece sorter may occupy a footprint or space which is substantially less than the length dimension of prior art mailpiece sorters.

In the context used herein, “mailpiece” means any sheet, page, document, or media wherein the dimensions and stiffness properties in a third dimension are but a small fraction, e.g., 1/100th of the dimensions and stiffness characteristics in the other two dimensions. As such, the mailpiece is substantially “flat” and flexible about axes parallel to the plane of the sheet. Hence, in addition to individual sheets of paper, plastic or fabric, objects such as envelopes and folders may also be considered “mailpieces” within the meaning herein.

The displacement system and sorting apparatus described and illustrated herein is described in the context of a mailpiece sorter, though the invention is applicable to any sheet handling device which sorts substantially rectangular sheets of material, i.e., sheets having a width dimension which is less than its length dimension. FIGS. 2, 3, and 4 illustrate a displacement module 10 that includes a series of cooperating elements 12 which act on a mailpiece 14 to transpose its orientation from a first on-edge orientation to a second on-edge orientation. In the context used herein, the mailpiece 14 is generally rectangular in shape such that one side is necessarily longer or shorter than an adjacent side. For example, a typical type-ten (No. 10) mailpiece envelope has a length dimension of about eleven and one-half inches (11.5″) and a width dimension of about four and one-half inches (4.5″).

The mailpiece 14 is fed and singulated in a conventional manner by a sheet feeding apparatus 16. The sheet feeding apparatus 16 feeds each mailpiece 14 in an on-edge lengthwise orientation towards the displacement module 10 which accepts the mailpiece 14 between or within coupled pairs of cooperating elements such as rollers 20 a, 20 b. Prior to being accepted within the displacement module 10, a scanner SC typically reads the mailpiece 14 and communicates the information to a processor 30 (FIGS. 2 and 4) for the purposes of performing a sortation algorithm. This sortation algorithm is subsequently used to control the various diverter mechanisms 26 (FIG. 2) within the sortation bin module 18.

Each coupled pair comprises a first pair of rollers 20 a defining an upper nip 22 a (see FIGS. 3 and 4) which accepts an upper portion 14U of the mailpiece 14 and a second pair of rollers 20 b defining a lower nip 22 b which accepts a lower portion 14L of the mailpiece 14. In the context used herein, a “nip” means any pair of opposing surfaces, or cooperating elements, which secure and hold an article, or portion of an article, therebetween. Consequently, a nip can be defined between rolling elements, spherical surfaces, flat bands or compliant belts.

As the mailpiece 14 traverses the displacement module 10, the coupled pairs 20 a, 20 b cooperate to linearly displace and rotate the mailpiece 14 along the envelope feed path EFP. As best seen in FIG. 3, five (5) pairs of upper rollers 20 a, and five (5) pairs of lower rollers 20 b, move the mailpiece 14 linearly along the sheet path SP. Simultaneously, or as the mailpiece moves from left to right in FIG. 3, several of the coupled pairs 20 a, 20 b rotate the mailpiece 14 about virtual axes VA to transpose its orientation from an on-edge lengthwise orientation to an on-edge widthwise orientation. To effect rotation, the displacement module 10 includes a means to differentially drive the coupled pairs 20 a, 20 b such that the lower portion 14L of the mailpiece 14 incrementally travels at a different, e.g., higher, speed or velocity. In the described embodiment, as each mailpiece 14, fed through the displacement module 10, reaches various threshold positions between the coupled pairs 20 a, 20 b, each of the lower pairs 20 b may be driven at a higher rotational speed relative to the respective upper pair 20 a.

More specifically, the processor 30 (see FIG. 4) is operative to control a plurality of rotary actuators or motors 32 which drive the upper and lower pairs 20 a, 20 b of rollers. The motors 32 may drive only one of the rollers in each of the pairs 20 a, 20 b, while the other roller serves as an idler to define the upper and lower nips 22 a, 22 b. As a mailpiece 14 moves along the feed path EFP and between the coupled pairs 20 a, 20 b, the motors 32 may be driven at the same or differential speeds to effect linear or rotational motion. For example, the motors 32 may be driven in unison such that both upper and lower portions 14U, 14L of the mailpiece 14 are displaced at the same speed. Under such control, the mailpiece 14 moves linearly from one coupled pair 20 a, 20 b to another pair 20 a, and 20 b. When the mailpiece 14 reaches a threshold position between a coupled pair 20 a, 20 b, the motors 32 may be differentially driven such that the upper and lower portions 14U, 14L of the mailpiece 14 are differentially displaced, e.g., the lower portion 14L moves at a higher speed than the respective upper portion 14U. Under this control, the mailpiece 14 rotates about the virtual axis VA such that the mailpiece changes orientation, e.g., is rotationally displaced.

In FIG. 5, a dimensionless speed profile of the coupled pairs 20 a, 20 b is depicted to demonstrate the method of motor control. Therein, the rotational velocity of the driven rollers 20 a, 20 b are plotted relative to the mean position of the mailpiece 14 along the envelope feed path EFP. Upon reaching the nips 22 a, 22 b of the upper and lower pairs 20 a, 20 b, the speed V1 of both pairs 20 a, 20 b is equal or matched such that the mailpiece 14 translates linearly without rotation. That is, each of the upper and lower portions 14U, 14L of the mailpiece is displaced at the same rate of speed. Upon reaching a threshold position between the upper and lower nips 22 a, 22 b of a subsequent or downstream pair of rollers 20 a, 20 b, the processor 30 drives the motors 32 to increase the rotational speed of the lower pair 20 b to a second speed V2, while decreasing the rotational speed of the upper pair 20 a to a third speed V3. The solid line SPL denotes the speed profile of the upper rollers 20 a, while the dashed line SPU represents the speed profile of the lower pair of rollers 20 b. This speed differential effects rotation of the mailpiece 14 as the mailpiece 14 continues to move downstream along the feed path EVP.

In the described embodiment, the second, third and forth pair of rollers 20 a, 20 b rotate the mailpiece, while the first and fifth pairs 20 a, 20 b effect pure linear translation of the mailpiece 14. While the amount of rotation effected by each of the cooperating pairs 20 a, 20 b may differ from an upstream pair to a downstream pair, in the described embodiment, each of the intermediate pairs 20 a, 20 b rotates the mailpiece about thirty degrees about the virtual axis VA Further, by examination of the speed profiles SPL, SPU, it will be noted that the profiles diverge or differ when the processor effects controlled rotation of the mailpiece 14 and may converge to the same speed to effect pure linear motion of the mailpiece 14. Moreover, it should also be noted that the speed of both pairs 20 a, 20 b remains positive (i.e., does not reverse directions) to continue linear movement of the mailpiece 14 along the feed path EVP while, at the same time, rotating the mailpiece 14.

Finally, it may be desirable to vary the separation distance between the upper and lower rollers 20 a, 20 b of each coupled pair. For example, to achieve a controlled rotation of the mailpiece 14, the separation distance SD2, SD3 of the second and third pairs 20 a, 20 b of rollers, i.e., from an upstream to a downstream pair, may increase to optimally control the displacement and rotation of the mailpiece 14.

In FIG. 6, an alternate embodiment of the invention is shown which includes a plurality of sensors disposed along the feed path EVP and between the coupled pairs 20 a, 20 b of rollers. Therein, rows of light detecting photocells OS1, OS2 sense the position of the mailpiece as it transitions from an on-edge lengthwise orientation to an on-edge widthwise orientation. The array of photocells OS1, OS2 is directed across the plane of the mailpiece 14 to detect the linear and angular position of the mailpiece leading edge 14L. Orientation signals are fed to the processor (not shown in FIG. 6) to determine whether the mailpiece is accurately or appropriately positioned relative to prescribed position data, i.e., a position schedule recorded and stored in processor memory.

If an error exists between the actual position and the scheduled position of the mailpiece 14, the processor may increase or decrease the differential speeds of a coupled pair to implement a corrective displacement/rotation. For example, the actual leading edge position of the mailpiece 14, shown in solid lines, may correspond to a first line AP intersecting photocells 26 a, 26 b. If, however, the scheduled position corresponds to a second line DP intersecting photocells 26 a′ 26 b′, the processor may change the speed profile SPU′ of a downstream pair of rollers to increase the speed of the lower rollers 20 b to a velocity V4. As such, the processor may implement an action to correct for deviations in mailpiece position or rotation i.e., as the mailpiece traverses from an intermediate upstream position to a subsequent downstream position.

In FIGS. 2 and 7, the displacement system 10, therefore, changes the orientation of the mailpiece 14 from an on-edge lengthwise orientation in the feeder 16 to an on-edge widthwise orientation for use in a bin/tray module 18. Additionally, the mailpiece sorter 40 (FIG. 2) can be adapted to include sortation bins/trays 44 which accept and stack the on-edge widthwise dimension of the mailpieces 14. Specifically, the sortation bins/trays 44 are adapted to support the short edge or width dimension W of the mailpiece 14 while guiding the long edge or length dimension L on each side thereof. That is, the base 44B of the bins/trays 44 support the on-edge width dimension W, while sidewall guides 44S, disposed at substantially right angles to the base 44B, support the length dimension L of each mailpiece 14.

Inasmuch as the widthwise dimension W (FIG. 7) of many mailpiece types can be significantly less than the lengthwise dimension L, the sortation bin module 18 can occupy less space or accommodate more sortation bins/tray 44. By examination and comparison of FIGS. 1 and 2, it will be appreciated that the mailpiece sorter 40 (FIG. 2), which incorporates the displacement system 10 of the present invention, can be combined with a bin module 18 having eight (8) additional sortation bins/trays 44. In FIG. 2, the additional bins/trays 44 are shown in dashed lines and in series with an upstream set of sixteen (16) bins/trays 44. Accordingly, twenty-four (24) sortation bins/trays 44 occupies the same space as the sixteen (16) bins 110 used in the prior art mailpiece sorter 100 (FIG. 1). Alternatively, the sortation bin 18 may occupy fifty percent (50%) less floor space than an equivalent sortation module of the prior art sorter 100.

Although the invention has been described with respect to a preferred embodiment thereof, it will be understood by those skilled in the art that the foregoing and various other changes, omissions and deviations in the form and detail thereof may be made without departing from the scope of this invention. For example, while the displacement system 10 of the present invention employs five (5) coupled pairs of rollers 20 a, 20 b, a greater or fewer number may be employed to transpose or change the orientation of the mailpiece. Furthermore, while the cooperating elements are shown to include coupled pairs of rolling elements, the displacement system may include a lower pair of rolling elements and an upper pair of compliant belts. According to this embodiment, the lower pair of rolling elements may be controlled to rotate the lower portion of the sheet material/mailpiece while the upper pair of compliant belts retains the position of the upper portion of the sheet material/mailpiece, thereby allowing the sheet material/mailpiece to rotate about a virtual axis. 

1. A system for transposing the angular orientation of mailpiece from a first orientation to a desired second orientation, comprising: a first pair of cooperating elements defining a nip for accepting a first portion of the mailpiece therebetween, a second pair of cooperating elements defining a nip for accepting a second portion of the mailpiece therebetween; a means for driving the first and second pairs of cooperating elements such that the first and second portions of mailpiece are each conveyed along a feed path at different speeds, thereby transposing the mailpiece about an axis and changing the angular orientation of the mailpiece.
 2. The system according to claim 1 wherein the nips are aligned in a vertical plane to transpose the sheet material from a first on-edge orientation to a second on-edge orientation.
 3. The system according to claim 2 wherein the cooperating elements include a first and second pair of rolling elements.
 4. The system according to claim 2 wherein the cooperating elements include a first pair of rolling elements and a second pair of compliant belts.
 5. The system according to claim 1 wherein the nips are co-planar and wherein the first and second pairs of rolling elements define a coupled pair, the system further comprising a plurality of coupled pairs sequentially arranged to receive, transpose and convey the sheet material along the feed path.
 6. The system according to claim 5 wherein the coupled pairs are operative to incrementally transpose the sheet material such that the sheet material assumes at least one intermediate position as the sheet material is conveyed along the feed path from an upstream position to a downstream position along the feed path; and further comprises: a sensing means for sensing at least one of intermediate position of the sheet material between the upstream and downstream coupled pairs and issuing an orientation signal indicative thereof; and a processor for storing prescribed position data indicative of a desired intermediate sheet material position between the upstream and downstream coupled pairs, the processor, furthermore, responsive to the orientation signal, for comparing the sensed intermediate position to the prescribed position data, for calculating a difference value therebetween, and for issuing an error correction signal, based upon the difference value, to the drive means for transposing the sheet material to the desired final orientation.
 7. The system according to claim 5 wherein the drive means varies the speed of rolling element pairs according to a speed profile, the speed profile of the rolling element pairs being characterized by the rolling element pairs being driven at a matched speed, during a first segment of the velocity profile, to translate each portion of the sheet material linearly, and being driven at a relative speed, during a second segment of the speed profile, to rotate and transpose the sheet material.
 8. The system according to claim 6 wherein the drive means varies the speed of rolling element pairs according to a speed profile, the speed profile of the rolling element pairs being characterized by the rolling element pairs being driven at a matched speed, during a first segment of the velocity profile, to translate each portion of the sheet material linearly, and being driven at a relative speed, during a second segment of the speed profile, to rotate and transpose the sheet material.
 9. The system according to claim 3 wherein the first and second pair of rolling elements define a separation distance therebetween, and wherein the separation distance increases from an upstream to a downstream pair.
 10. A mailpiece sorter, comprising: a feeder module for feeding and singulating mailpieces from a stack of mailpieces, each mailpiece being fed along a feed path in a first on-edge orientation; a sortation bin module for accepting and diverting the mailpieces into one of a plurality of sortation bins, each sortation bin having a base for supporting a second on-edge orientation of each mailpiece; and a means for displacing each mailpiece traveling along the feed path from the feeder module to the sortation bin module and transposing each mailpiece about an axis to change the angular orientation thereof from the first to the second on-edge orientation.
 11. The mailpiece sorter according to claim 10 wherein the displacement means includes: a first pair of cooperating elements defining a nip for accepting a first portion of each mailpiece therebetween, a second pair of cooperating elements defining a nip for accepting a second portion of each mailpiece therebetween; a means for driving the first and second pairs of cooperating elements such that the first and second portions of each mailpiece are each conveyed along a feed path at different speeds.
 12. The mailpiece sorter according to claim 11 wherein the nips are aligned in a vertical plane.
 13. The mailpiece sorter according to claim 11 wherein the cooperating elements include a first and second pair of rolling elements.
 14. The mailpiece sorter according to claim 11 wherein the cooperating elements include a first pair of rolling elements and a second pair of compliant belts.
 15. The mailpiece sorter according to claim 10 wherein the nips are co-planar and wherein the first and second pairs of rolling elements define a coupled pair, the system further comprising a plurality of coupled pairs sequentially arranged to receive, transpose and convey the mailpiece along the feed path.
 16. The mailpiece sorter according to claim 15 wherein the coupled pairs are operative to incrementally transpose the mailpiece such that the mailpiece assumes at least one intermediate position as the mailpiece is conveyed along the feed path from an upstream position to a downstream position along the feed path; and further comprises: a sensing means for sensing at least one of intermediate position of the mailpiece between the upstream and downstream coupled pairs and issuing an orientation signal indicative thereof; and a processor for storing prescribed position data indicative of a desired intermediate mailpiece position between the upstream and downstream coupled pairs, the processor, furthermore, responsive to the orientation signal, for comparing the sensed intermediate position to the prescribed position data, for calculating a difference value therebetween, and for issuing an error correction signal, based upon the difference value, to the drive means for transposing the mailpiece to the desired final orientation.
 17. The mailpiece sorter according to claim 15 wherein the drive means varies the speed of rolling element pairs according to a speed profile, the speed profile of the rolling element pairs being characterized by the rolling element pairs being driven at a matched speed, during a first segment of the velocity profile, to translate each portion of the mailpiece linearly, and being driven at a relative speed, during a second segment of the speed profile, to rotate and transpose the mailpiece.
 18. The mailpiece sorter according to claim 16 wherein the drive means varies the speed of rolling element pairs according to a speed profile, the speed profile of the rolling element pairs being characterized by the rolling element pairs being driven at a matched speed, during a first segment of the velocity profile, to translate each portion of the mailpiece linearly, and being driven at a relative speed, during a second segment of the speed profile, to rotate and transpose the mailpiece.
 19. The mailpiece sorter according to claim 13 wherein the first and second pair of rolling elements define a separation distance therebetween, and wherein the separation distance increases from an upstream to a downstream pair. 